Consumer products can provide a hospitable environment for rapid microbial growth. Such exposure can, and frequently does, result from inadvertent microbial inoculation of the product during manufacturing or packaging. Spoilage microorganisms, for example in food or beverage products, can then rapidly proliferate by feeding on nutrients provided by the product.
Preservatives, such as sorbates, benzoates, organic acids, and combinations thereof have been used in various products, particularly foods and beverages, to provide some degree of microbial inhibition. At levels effective to inhibit microbial growth, some of these preservatives can contribute off-flavors in the product, thus making the product undesirable for its intended purpose. For example, accepted usage levels for potassium sorbate is typically in the range of from about 200 ppm to about 3000 ppm. However, at the higher end of this accepted usage range, potassium sorbate can contribute to off-flavors in the foods or beverages.
Additionally, certain preservative systems are not effective in the presence of fortification components, including various vitamins and minerals. For example, calcium fortification in certain food or beverage products can render the preservative system inactive, thereby failing to inhibit microbial growth. Therefore, wherein nutrient fortification is desirable, expensive preservative components such as dimethyl dicarbonate (DMDC) must be utilized to inhibit microbial growth in the fortified product.
It has been disclosed that oil of mustard, which contains isothiocyanates, exhibits an antibacterial and antimycotic effect in oral therapies and on certain foods. See e.g., Sekiyama et al., U.S. Pat. No. 5,334,373, assigned to Nippon Sanso Corp., issued Aug. 2, 1994; and Madaus et al., U.S. Pat. No. 3,998,964, issued Dec. 21, 1976. However, it has been suggested that mustard oil can irritate the mucous membranes and may not be well tolerated by individuals ingesting the oil. See e.g., Madaus et al. Additionally, mustard oil can exhibit strong characteristic flavors which render the oil unfavorable for use in food or beverage products. Accordingly, mustard oil has not been widely known or widely utilized in the art for its antibacterial and antimycotic effect, particularly in products suitable for ingestion such as food and beverage products.
However, the present inventors have surprisingly discovered that one or more isothiocyanate compounds, optionally in combination with a sorbate and/or benzoate preservative, exhibits a strong antimicrobial effect without imparting off-flavors or offensive odors in the final product. In doing so, the present inventors have discovered a synergistic relationship between the relative effects of each of the preservative components when utilized in combination. Surprisingly, when utilized in combination, each of the preservative components are effective at levels low enough to maintain the organoleptic integrity of the final food or beverage product. The present inventors have further surprisingly discovered that such antimicrobial effect is maintained even in the presence of fortification nutrients such as calcium, thus overcoming the problems associated with currently fortified products. Accordingly, the preservative systems of the present invention are utilized at relatively low levels, provides maintenance of flavor and odor integrity, and are effective against microbial growth even in the presence of fortification nutrients.